How contagious is this?
A hazelnut is based on an exuberant reaction of the body’s immune system and is not contagious. It cannot be transmitted to other people. However, the tendency to allergies is often genetically inherited, so that family clusters of hazelnut allergies can occur.
However, this is not a disease with which the children of allergy sufferers are infected. Rather, the genetic predisposition is passed on from parents to children, so that they too can develop hazelnut allergies.
